Re: Making vertical-border char defcustom?

[Eli Zaretskii]

> From: Paul W. Rankin <address@hidden>
> Date: Mon, 20 Jan 2020 00:13:27 +1000
> 
>    (defun prettify-vertical-border (&optional dummy)
>      (ignore dummy)
>      (set-display-table-slot
>       (or buffer-display-table standard-display-table)
>         'vertical-border ?│))
> 
>    (when (not window-system)
>      (add-hook 'window-configuration-change-hook
>                'prettify-vertical-border)
>      (add-hook 'change-major-mode-hook
>                'prettify-vertical-border))
> 
> However the problem with this approach is that some major/minor-modes
> set their own overriding display-table... I think help-mode or
> special-mode...

I don't understand the difficulty.  AFAIU, all you need is augment
your prettify-vertical-border with a call to window-display-table, and
then no overriding could get in your way.  Or am I missing something?